Tom,This is from a previous post by 72Westie:The pipe is a stepped head pipe, 1 5/8 out of the head to 1 3/4. They have a 2 1/4 full length heat shield back to the muffler, that is what gives the head pipe that big look. He said they tried a bunch of different sizes and this was the best set-up.

And the Hitchcock's pipe has the solid reducer inside it, which can be bored to 1 5/8".

So, it appears that we'll be compatible on both counts, as far as I can tell.I would prefer to check the fit in the head first, before I make any firm statements. This should happen soon. No need to jump the gun.

No, they will use the valve lash caps on top, so that does away with any special hardness needs. The lash caps are hardened.The keeper grooves can be cut into the existing hardness level without worry.

I'm out.I believe that'll be great for a track bike, but, not for my daily rider.Fin.

I understand. No hard feelings.There's always a line involved in modifications which some people feel is too far, and others feel is not far enough. It's a hard line to walk.

I'm sure that there will be other factors which cause people to not choose it.As things zero-in on that line, and it becomes clearer, this acts like a wedge on the prospective clients, and some will decide against it.I had to live with that situation when doing the Fireball too. Settling on one set of parameters will always have this effect.

The one thing that I can say about it is that the cams are short duration, and they have a short overlap. The added lift and port shape/size which we are planning is really necessary to provide the power boost in the absence of longer cam duration. Keeping the short duration and overlap does help to maintain the lower rpm torque, and more lift/flow helps to increase torque in the midrange too.It's a juggling act. There are always ramifications to each decision.

Regarding the valves, they are not enlarged, and the intake is 1.733" and the exhaust is 1.5".The inconel is not required for the temperature issues that they normally are used for, but they had the high quality inconel blanks in a size that we needed, which could be easily provided for our application without long waiting times, and the cost difference was only a few dollars per valve. So, we have a bit of "overkill" in the valve material, but it isn't a budget buster, and the valves will be very robust in terms of handling any temps that they will see in this application.

I take it you are grinding your very own cams for this project? If so, what was the biggest variation as far as the lift/duration between the original cams and new cams? Have you tried any variations to perform better at higher RPMs or are you just focused on making the most out of low end and mid range RPMs?Scottie

I take it you are grinding your very own cams for this project? If so, what was the biggest variation as far as the lift/duration between the original cams and new cams? Have you tried any variations to perform better at higher RPMs or are you just focused on making the most out of low end and mid range RPMs?Scottie

Hi Scottie,We are not grinding cams for this project because the auto-decompressor system is located inside the exhaust cam, and that complicates the cam-making procedure. And we don't want to delete the auto-decompressor because that protects the electric starting gear system from damage.We plan to address the lift and breathing issues in a different way with this engine, and leave the original cams in place, along with the auto-decompressor.

However, for the older Iron Barrel engines we had cams ground for us called "Ace Magnum Cams" which have about .040" higher lift, and about 8 degrees longer duration, compared to the stock cams. And the opening/closing timing points are different than stock, and the ramps and lobe shapes are different than stock. These things are determined by the flow characteristics of the ports, so that we can make the most out of the flow, without putting any higher stress than necessary in the valve train components. These cam figures might not sound all that impressive for an increase, but it must be viewed in the context that we are flowing about 30% more through the ports on average, because of our head work.

On the Fireball, we focused on a wide torque curve, with an upper-rpm range raised to about 6000 rpm, and peaking horsepower relatively near the max rpm of the engine. This gave a good result for street use, and still allowed a good higher rpm power, and the ability to get a top speed of over The Ton.

We have good understanding of cam design, and so we can apply that to our needs, whether they be higher rpm power, or low rpm torque, or whatever. In the end, the cams are basically the "traffic cop" of breathing, and ultimately it is the flow capacity and the flow characteristics in the head which will determine the power potential and power range of the engine.

With the Bullet, the long stroke is a limiting factor in rpms, so the max rpms are not really going to get very high. So with the normal 90mm stroke that all the Bullet engines have, we consider 6000-6500rpm to be about the safe limit for a street rod, while keeping engine longevity in mind as one of the goals. Generally we aim for 6000 rpm limit, and give a few hundred extra rpms for a useful extra "cushion" if needed for some reason on occasion.With this approach, we can get a nice power level at the higher rpms, without objectionable losses down there in the lower rpms, and good street tractability, good fuel economy, and a good expectation of longevity.